Lubricant packed bumper sub



E. C. GREENWOOD LUBRICANT PACKED BUMPER SUB Aug. 15, 1961 Filed June 5,1957 A, FIG. I

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LUBRICANT PACKED BUMPER SUB Filed June 3, 1957 3 Sheets-Sheet 2 INVENTOREugene (1 Greenwood ATTORNEY) Aug. 15, 1961 E. c. GREENWOOD LUBRICANTPACKED BUMPER SUB 5 Sheets-Sheet 3 Filed June 5, 1957 EUGENE Clfiessuwoag INVENTOR.

w M w. \\E\\ /1A/ El. WW .Ew .W. v #v% J Ag g 4 4. a M M M Mi M w 4United States Patent 9 i 2,996,131 LUBRICANT PACKED BUMPER SUB Eugene C.Greenwood, Balboa, Calif. (413 Poinsettia St., Corona del Mar, Calif.)Filed June 3, 1957, Ser. No. 663,576 24 Claims. (Cl. 175-493) Thisinvention relates to a lubricant packed bumper sub. More particularly,the invention relates to means for protecting the splines of the bumpersub from abrasive material present in an oil well, and also relates tonovel pressure-equalizing, wear-compensating, knocker head and wipermeans. This application constitutes a continuation-in-part of myco-pending application, Serial No. 545,271, filed November 7, 1955, andnow abandoned.

In the oil well drilling art it is highly important that the splineswhich associate the upper and lower components of a bumper sub beprotected from the sand, dirt, and other abrasive material in the well.If the splines are not protected and lubricated they wear with greatrapidity, necessitating frequent replacement of the bumper sub orcomponents thereof. Despite this need for a bumper sub in which thesplines are properly sealed and lubricated, it has not heretofore beenknown how to construct a lubricant packed bumper sub which will operateproperly in tne drilling string during all normal operations thereof. Inthis connection it is pointed out that bumper subs, which are present inthe drilling string during normal operation, are to be contrasted withoil well tools known as jars, which are only placed in the drillingstring during abnormal conditions such as when the drill bit is stuck.

In view of the above factors characteristic of bumper subs, it is anobject of the present invention to provide a bumper sub which is sealedand packed with lubricating fluid in order to prevent abrasion of thesplines by material present in the well and which is so constructed thatrelative reciprocation of the upper and lower bumper sub components isnot impeded by the lubricating fluid.

A further object is to provide a bumper sub incorporating novelpressure-equalizing means in combination with large area passage meansfor the lubricating fluid.

An additional object is to provide a bumper sub incorporating means forcompensating for the wear on the splines or keys, in combination withmeans for effecting communication between opposite end portions of thebumper sub through large area spline passages.

A further object is to provide a bumper sub incorporating novel knockerhead means in combination with lubricant reservoir means forreplenishing the supply of lubricating fluid in the region of thesplines.

An additional object is to provide an improved bumper sub which operatessatisfactorily in deep wells for long periods of time without excessivewear, which prevents transmission of substantial shocks from the drillbit to portions of the drill string above the bumper sub, whichmaintains the drilling weight on the drill bit at a desired value, whichis operable to dislodge a drill bit when the same becomes stuck, andwhich is used constantly during normal drilling operations so that itneed not be specially inserted into the drilling string when stickingoccurs.

It is a further object of the invention to provide a fluid packed bumpersub in which the tubular parts have free sliding action without thelubricant therein imparting a buffer or damping action.

It is another object of the invention to provide an improved bumper subfor drilling strings, and which is durable, non-wobbly and efficient inaction.

A further object of this invention is the provision of a a bumper subhaving relatively slidable tubular parts for the purpose of impactjarring, and including a self-con- Patented Aug. 15, 1961 tained closedand sealed lubricating system for the spline areas of the tubular parts.An auxiliary lubricating reservoir is provided for maintaining thelubricant in full supply in the spline area by replenishing lubricantwhich seeps past the packing.

A further object of this invention is the provision of an improvedbumper sub, the outer tubular part of which is provided with wiper ringsfor maintaining the mandrel tube substantially free of mud, etc., in thearea between the striking faces of the outer tube and mandrel.

An important object of this invention is the provision of a bumper subin which the reciprocating action of the mandrel and drive sleeve isfree of any fluid butler action, whereby there may be quick relativeaxial movement between these parts.

A further object of this invention is the provision of a bumper sub soconstructed as to allow exact control of weight upon the bit.

A further object of this invention is the provision of a bumper subwhich will enable the operator to have constant pipe motion in the wellbore during use of the bumper sub, whereby the drill tubing above thebumper sub will not become stuck within the drill bore.

A further object of this invention is the provision of a bumper subwhich, because of free sliding action of the parts, relieves strainsupon the derrick, drilling lines, swivel bearings, etc.

Other objects and advantages of this invention will be apparent duringthe course of the following detailed description.

In the accompanying drawings, forming a part of this specification, andwherein similar reference characters designate corresponding partsthroughout the several views:

FIGURE 1 is a vertical longitudinal sectional view taken through thebumper sub, showing the position of the parts for downward impactmovement. In this view the chamber between the packings is shown free oflubricant to better expose details and relation of the arts.

FIGURE 2 is a side elevation of the mandrel tube of the bumper sub. Itmay be of one piece construction.

FIGURE 3 is a fragmentary longitudinal cross-sectional view takenthrough the bumper sub, with the parts in position for upstroke impact.In this view lubricant is shown in the space locations occupied by it.

FIGURES 4, 5, 6, 7 and 8 are enlarged transverse crosssectional views,taken substantially on the respective cross-section lines shown inFIGURE 1 of the drawings.

FIGURE 9 is a vertical cross-sectional view taken through the bumper subdrive sleeve. This is a detachable part for connection with the lowerend of the barrel of the drilling equipment. While this view shows onlythe drive sleeve, it is taken in a plane through the drive sleeverepresented by the line 9-9 of FIGURE 7.

FIGURE 10 is an enlarged fragmentary cross-sectional view taken througha detail of the knocker head substantially on the line 10-10 of FIGURE3.

FIGURE 11 is a transverse cross-sectional view taken substantially onthe line 11-1l of FIGURE 1.

FIGURE 12 is a longitudinal sectional view illustrating a secondembodiment of the invention, incorporating pressure-equalizing means andwear-compensating means, the section being taken generally along thebroken line indicated at 1212 in FIGURE 15. In this view the tool isshown closed, and the sliding packing is in a position normally assumednear the top of a well.

FIGURE 13 illustrates the embodiment of FIGURE 12 but with the mandrelin the opposite extreme position (open) relative to the barrel and drivesleeve, and illustrating the sliding packing at a position normallyassumed at the bottom portion of an oil well.

FIGURE 14 is an enlarged longitudinal section of the pressure-equalizingsliding packing means employed in the embodiment of FIGURES 12-17.

FIGURE 15 is an enlarged horizontal sectional view taken on line 15-15of FIGURE 12.

FIGURE 16 is a sectional view taken on line 16-16 of FIGURE 12, andshowing the combination splineways and lubricant passages.

FIGURE 17 is a sectional view corresponding generally to FIGURE 16 butillustrating the condition of the components after the splines on thedrive sleeve have been shifted to new splineways in the mandrel, thuscompensating for the effects of wear between the mandrel anddrive-sleeve splines.

Referring first to FIGURES lll, wherein for the purpose of illustrationis shown a first embodiment of the invention, the letter A may generallydesignate the improved fluid packed bumper sub. Its main structuralfeatures include a barrel B, drive sleeve C, mandrel D, and knocker headE.

The barrel B is of conventional construction, including the upperportion 15 forming a tool box joint for the drilling string and having adrilling fluid passageway 16 therethrough. Its lower end is providedwith an internally screw threaded tapered socket #17 to receive theupper screw threaded tapered end 17a of the drive sleeve C. The barrel Bbelow the upper coupling is provided with a cylindrical passageway orchamber 13 of uniform diameter down to the joint socket 17.

The drive sleeve C is of substantially uniform external diameter havinga tapered screw threaded end 17a for coupling to the barrel B. It isprovided for its major length with a cylindrical passageway 20. Annulargrooves 21 (FIGURE 9) are provided just inwardly from the lower strikingface or margin 22, adapted to receive wiper rings 23, best shown inFIGURES l and 3 of the drawings, for the purpose of continuously wipingthe lower part of the mandrel D during axial reciprocatory movement ofthe parts B and C. The wiper rings, which may comprise split O-rings(FIGURE 11), are adapted to transmit pressure therepast, and do notfunction as seals.

The passageway 24 at the upper end of the drive sleeve C, for a distancedesignated at x in FIGURES 1, 3 and 9 of the drawings, is slightlyrestricted and has longitudinally extending spline keys 25 therein forthe distance x. These splines or keys 25 are shown in the drawings asthree in number, but need not necessarily be restricted to that number.In width they form a relatively small segment of the total circumferenceof the passageway 24. In the illustrated sleeve C, with an externaldiameter of 6%, the individual widths of these keys 25 are each 1l /2 ofthe 360 circumference of the passageway 24. They are uniformly spaced oncenters 120 apart, and therefore the passageway spaces between adjacentsplines, three in number, each form an arc of 108 /2". These spaces areimportant, because they form area in the lubricating chamber between themandrel and the barrel and drive sleeve along which lubricant may havefree passage during reciprocatory or axial movement of the bumper subtube parts.

It will be noted from FIGURES 1 and 3 of the drawings that the diameterof the passageway portion 24 of the drive sleeve C is less than thediameter of the passageway or chamber 18 through the lower part of thebarrel B. This leaves exposed in the barrel an upper annular strikingface on the top margin of the drive sleeve C. against which the knockerhead E strikes during upstroke jarring action, represented by theposition of the parts shown in FIGURE 3.

Referring to the mandrel or inner tubular part D, shown by itself inFIGURE 2, the same lengthwise thereof is provided with a drilling fluidpassageway 40. The mandrel has an enlarged lower end 41 provided with atool joint pin 42. Thereabove it has an externally smooth cylindricalsleeve portion 43 of less diameter than the portion 41. At the junctureof these portions 41 and 43 there is an upwardly facing annular strikingface 44 which is adapted to be engaged by the striking face 22 of thedrive sleeve C on the down stroke movement of the drive sleeve. Theportion 43 is annularly cut at 45 (FIGURE 2) close to the upper endthereof for receiving ring shaped packing 46, acting as a bottom sealfor the lubricating chamber of the bumper sub in a manner to besubsequently described. The sleeve portion 43 has a sliding fit in thepassageway 26 of drive sleeve C, as shown in FIGURE 1. Thus the wiperrings 23 will continually clean off the external surfacing of sleeveportion 43 during reciprocation of the inner and outer tubular partsforming the bumper sub.

The mandrel D above the packing 46, for the distance y, is provided withsplines and splineways for slidably receiving the spline keys 25 of thedrive sleeve C. At three locations externally on the mandrel D there areprovided spaced pairs of spline projections 50 and 51 defining a key way52 therebetween for receiving a spline 25 of the drive sleeve. Thewidths of these individual key or spline projections 50 and 51 may beabout the same as the widths of keys 25, or slightly greater in width.Thus, when the splines 25 interfit in the splineways 52 of the mandrelthere will be three spaces, each of a degree represented by are 2. Thesplines 25, 50 and 51 interfit, as is shown in the cross-sectional viewof FIGURE 7. These areas z provide unobstructed passageways forlubricant without damping or buffing action, during relative sliding ofthe drive sleeve C upon the mandrel D, in order that there will be freetransfer of lubricant from one side of the closed lubrieating chamber tothe other side along the spline areas.

The mandrel D, above the section y along which the splines areexternally provided, is undercut to provide an annular groove 62) shownin FIGURE 2, wherein is disposed the knocker head E. As is shown in thecross-sectional view of FIGURE 6, the knocker head E is a divided orsplit ring composed of segments or sections 63 and 64 adapted to seat inthe groove 60 and annularly projecting therefrom. The diameter of thesections 63 and 64 is such that when seated upon the mandrel they willhave a rather close but sliding fit engagement with the wall of thechamber 13 in the barrel B.

It will be noted that when the segments 63 and 64 are located in thegroove 60 their ends will lie spaced as at 66 (FIGURE 6). These spaces66 are lubricant passageways for replenishing the supply of lubricant tothe spline areas of the inner and outer tubular parts of the bumper sub.In order to hold the knocker head segments against rotation there isprovided a key 62. detachably secured by a screw 62a to one of thesegments. It seats in an extension of a splineway 52 above the knockerhead (see FIGURES 3 and 10). The spline keys and ways of the mandrel maybe continued above the under cut or annular groove 60 if so desired.

Above the knocker head E the mandrel has an elongated diametricallyreduced portion 70, the external wall of which faces the passageway 18through the barrel B in considerably spaced relation to define anauxiliary lubricant reservoir, indicated at 71 in FIGURES l and 3. Abovethe reduced portion 70 the mandrel D is provided with relatively spacedannular grooves 71a and 72, adapted to receive split snap rings 73 whichannularly project from the outer surface of a raised portion 74. Theydetachably hold a packer ring 76 which is faced on each side with packersupporting rings 77 and 78. The packer 76 embraces the wall of thechamber 18. it should be noted that the diameter of the passageway orchamber 18 is the same as the diameter of the passageway 20 of the drivesleeve wherein the packing 46 slides.

From the foregoing it will be apparent that there is a sealedlubricating chamber in the bumper sub between cant act as a buffer or adamper necessitating tensioning of the drill line in-. order to impactthe striking faces.

For up stroke movement, represented by the arrangement of parts inFIGURE 3, the operator pulls the line for striking the face 30 at thetop of the drive sleeve C against the projecting under surface of theknocker head E. The downward jarring action is imparted by lowering thebarrel and drive sleeve for contact of the striker surface 22 of thedrive sleeve against the mandrel striking surface 44.

From FIGURE 1 it will be noted that when the surfaces 22 and 44 are incontact the spline area x assumes the position shown. Thus, there is anarea in the sealed lubricating chamber below the interfitting splinesWhereat a filler plug 80 is provided for adding lubricant to thelubricating chamber in the tool at time of servicing.

The axial reciprocating movement of the inner and outer tubular parts ofthe bumper sub is a quick action in contradistinction to locked jars,due to free lubricant passage from one side or end of the spline area tothe other. The bumper sub is installed in the drill string above thedrill bit, but with sections of pipe interposed between the bit andbumper sub. These pipe sections equal, together with the weight of themandrel, the weight (drilling weight) desired to rest on the bit.

The bumper sub will allow exact control of weight on the bit because thedesired drilling weight (the weight supported by the drill bit) liesbelow the bumper sub. When the bumper sub is touched closed (i.e. withsurfaces 22 and 44 in light, not pressure, contact) in the positionshown in FIGURE 1 the only weight supported on the bit will be that ofthe mandrel D and other units between mandrel and bit. As the bit drillsinto the earth the bumper sub opens, maintaining the same weight on thebit. When the bumper sub has completely opened, this weight will besupported on the knocker head E and it will show on the Weight indicatorat the top of the well, the drilling weight then being added to that ofthe string. The pipe can be then lowered again, closing the tool. Thisoperation is repeated as the bore is drilled. This relieves the drillerof considerable effort, it being necessary to change the position of thepipe line far less frequently than without the bumper sub of thisinvention. Thus, wear is saved on the brake and other equipment.

With this bumper sub the drill string can be quickly and continuallyraised and lowered without much effort. Keeping the pipe in such motionwill result in less likelihood of it being frozen in position.

As drill bits turn on the bottom of the bore they often bounce and jump,setting up powerful vibrations throughout the entire drilling strings.This works a greater strain on the derrick, drilling lines, swivelbearings, etc. With the improved bumper sub much of such verticalvibrations will be damped out as the bumper sub opens and closes withthe motion of the pipe.

It is to be understood that all parts of the bumper sub are of metalexcept the packing and wiper rings.

Embodiment of FIGURES 12-17 Except as specifically indicated, theembodiment of FIGURES 12-17 is the same as the embodiment described withreference to FIGURES l-l 1.

In the present embodiment, the barrel has been given the referencenumeral 100, the drive sleeve 101, the mandrel 102 and the knocker head103.

Barrel is substantially identical to the barrel 1;- described inconnection with the first embodiment. The drive sieeve 101, however, isformed in two components 106 and 107, which are removably coupled toeach other by the tapered threaded socket means 108. The lower drivesleeve component 106 corresponds to the lower tubular portion of thedrive sleeve C of the first embodiment, having an internal passage 20the diameter of which is equal to the diameter of passage 18 in thebarrel 100. The making of passages 18 and 20 equal in diameter prevents,both in the present embodiment and in the previous one, the creation ofan undesired piston or pumping action during relative reciprocationbet-ween the mandrel and the outer tubular component comprising thebarrel and drive sleeve.

The splined or upper drive sleeve component 107 corresponds generally tothe upper portion of drive sleeve C described in connection with theprevious embodiment, except for a different spline construction as willbe described hereinafter. Drive sleeve component 107 thus has aninternal passageway 24 the diameter of which is less than the diameterof the passages 18 and 20, forming the upper annular striking face 30 atthe upper end of drive sleeve component 107. The formation of the drivesleeve in the two components 106 and 107 permits replacement of thesplined component 107 while retaining the lower component 106, as willbe described subsequently.

The wiper rings 23 of the previous embodiment are not incorporated inthe present one, so that the lower end of drive sleeve component 106 isnot internally grooved. The lower end is, however, provided with theradial striking face 22 adapted to engage striking face 44 of themandrel.

The mandrel 102 is diflerently splined than the mandrel of the firstembodiment, as will be set forth in detail hereinafter, and is alsomodified so that it may be provided with the pressure equalizing slidingpacking 111 which forms an important feature of the present embodiment.More particularly, the reduced upper portion 112 of mandrel 102 isformed with a cylindrical external surface of uniform diameterthroughout its length. A metal packing sleeve or ring 113 (FIGURE 14) ismounted slidably around such reduced portion 112, so that it may freelyslide between the upper ends of the splines on the mandrel and a snapring 114 provided at the upper mandrel end. Leakage of lubricant or mudbetween the metal ring 113 and the outer surface of portion 112 isprevented by O-rings 116 provided interiorly at the up per and lowerends of the ring 113.

On its outer side, the packing ring or sleeve 113 is formed with anannular recess 117 in which suitable packing means 118 are provided.These packing means, which may correspond to packing means 119 in thelower portion of the mandrel (corresponding to packing 46 of the firstembodiment), preferably comprise a plurality of elastoineric chevronelements 121 facing in opposite directions relative to a horizontalcentral plane. The packing means 118 bear slidably against the wall ofpassage 18.

The knocker head 103 is similar to the one described in connection withthe first embodiment, and incorporates two split or half rings 122 and123, each of which is slightly less than a semi-circle. These ringelements 122 and 123 are inserted in corresponding notches at the upperend portions of the mandrel splines, so that longitudinal movement ofthe split rings relative to the mandrel is positively prevented. Inorder to prevent rotational movement of the split rings in theirnotches, keys 124 are integrally provided on the upper surfaces of thesplit rings, and rest in the spline ways between the mandrel splines.

The keys 124 hold the split rings 122 and 123 in such rotated positionsthat passages 126 (FIGURE 15) of equal cross-sectional area are providedbetween the opposed end faces of the split rings. Such passages 126permit flow of replenishing lubricant from the reservoir 71 into thelubricating chamber between the mandrel and the outer tubular componentformed by the barrel and drive sleeve.

There will next be given a detailed description of the spline or keymeans, and the passage means, in the mandrel and drive sleeve. Thecentral portion of mandrel 102, below reduced portion 112 and above thelarger diameter portion 43, has an outer surface 127 of uniform diameterexcept where splined (FIGURE 16). A plurality of splines 128 extendlongitudinally of such central mandrel portion and project radially ofthe outer surface 127, terminating at surfaces 129 which are spacedradially inwardly from the walls of the barrel and drive sleeve passages18 and 20, respectively. More specifically, the outer spline surfaces129 lie along a cylinder the diameter of which is only slightly lessthan the diameter of passage 24 in drive sleeve portion 107.

Drive sleeve portion 107 is provided with longitudinal splines 131 whichcorrespond in shape to the splineways or passages between mandrelsplines 128, and fit therein as illustrated in FIGURE 16. Thus, theinner surfaces of splines 131 fit slidably against the outer surface 127of the central mandrel portion, just as the outer surfaces 129 of themandrel splines fit slidably against the wall of passage 24 in drivesleeve portion 107 It is an important feature of the present embodimentthat the number of mandrel'splines 128 is a multiple of the number ofdrive sleeve splines 131, and that the splines are so spaced andconstructed that the channels between the mandrel splines 128 servealternately as splineways for the drive sleeve splines and as passagesfor lubricant. Preferably, there are three equally spaced drive sleevesplines 131 (FIGURE 16) and six equally spaced mandrel splines 128.Also, preferably, the splines and splineways each initially occupydegrees. Thus, when the mandrel and the drive sleeve are related asillustrated in FIGURE 16, there will be three lubricant passages 132between various pairs of mandrel splines 128. However, upon rotation ofthe drive sleeve sixty degrees with relation to the mandrel, lubricantpassages 132 become splineways for drive sleeve splines 131, and thereare three other lubricant passages 133 (FIGURE 17) between other pairsof mandrel splines 128. Accordingly, the lubricant passages 132 and 133serve selectively as lubricant passages and as splineways for themandrel splines, depending upon the rotated position of the mandrelrelative to the drive sleeve.

Assuming that the parts are initially assembled as illustrated in FIGURE16, the rubbing radial surfaces of the mandrel and drive sleeve splinesmay wear after a substantial length of time, particularly if thereshould be a packing failure and consequent entrance of mud into thetool. Such wear will be much greater for the drive sleeve splines 131than for the mandrel splines 128, due to the longer length of thelatter. After a certain amount of such wear has occurred, the tool isdisassembled and a new upper drive sleeve component 107 is substitutedfor the worn one, this being possible because of the provision ofthreaded socket means 108. The bumper sub is then reassembled but withthe new drive sleeve splines 131 inserted, as illustrated in FIGURE 17,in the spaces or gaps between the mandrel splines which formerly served(FIG- URE 16) as the lubricant passages 132. Thus, insofar as the matingspline surfaces are concerned, a completely new tool is achieved bysubstituting only a relatively short and inexpensive component 107. Thewear causes lubricant passages 133 to be somewhat increased in size, asillustrated in phantom lines in FIGURE 17, but this produces no harmfuleffect whatsoever and instead increases the freedom of lubricant passageas desired. The described wear compensating means has the effect ofgreatly prolonging the life of the tool without replacing the mandrel,which is very expensive as compared to the drive sleeve component 107.

The lubricant passages 132 or 133 have a combined cross-sectional areasufiiciently large to permit free communication of fluid between thelubricant chambers 134 and 136 which are defined between the inner andouter tube components above and below drive sleeve portion 107,respectively. These large-area passages have the effect, as previouslydescribed and as will be indicated hereinafter, of preventing a dampingor dashpot action as the inner tubular member (mandrel 102) and outertubular member (barrel and drive sleeve 101) are reciprocated ortelescoped relative to each other.

When the bumper sub is shifted from its closed position illustrated inFIGURE 12, with the striker faces 2 and 44 in engagement, to the fullyopen position shown in FIGURE 13 and with the striker face 30 inengagement with the split rings 122 and 123, lubricant flows freely fromchamber 134 to chamber 136 through the passages 132 or 133 as the casemay be. Since the lubricant flows freely through passages 132 or 133,there is no piston action tending to force lubricant through passages126 (FIGURE 15) into the reservoir 71 and thus against the slidingpacking 111. The free communication between chambers 134 and 136, whichchambers are equal in cross-sectional area when viewed in horizontalplanes, thus affords two beneficial results, the first of which is toprevent a dash-pot action as the components are reciprocated, and thesecond of which is to prevent undesirable inter-action with the pressureequalizing sliding packing 111. With relation to the latter beneficialresult, it is to be understood that the full benefits of the slidingpacking 111 are achieved because of the free communication through thespline passages 132 and 133. For example, wear on O-rings 11s isminimized.

Proceeding next to an additional description of the func tion of thepressure equalizing sliding packing 111, the position of such packing onthe upper mandrel portion 112 is independent of the position of themandrel 102 relative to the barrel 100 and drive sleeve 101. Statedotherwise, the position of the sliding packing 111 is a function of thedepth to which the bumper sub is lowered into the well, the diameters ofpassages 18 and 20 and other factors which, because of the freecommunication through passages 132 and 133, bear no relation to thedegree of telescoping of the bumper sub components.

Before the bumper sub is inserted into the well, it is completely filledwith lubricant introduced through the fill plug 80. Such filling iseffected with sliding packing 111 in abutment with snap ring 114.However, because of the effects of air trapped in the lubricantchambers, leakage past the packings 118 and 119, etc., the slidingpacking 111 will be forced downwardly by the hydrostatic pressure afterthe bumper sub is lowered into the well. The position of the packing 111is accordingly such that the external and internal pressures are alwaysequal, both at the bottom of the Well when the packing 111 may be in alow position as shown in FIGURE 13, and at or near the top of the wellwhen the packing may be in a high position such as is shown in FIGUREl2. This pressure-equalizing action has the very desirable effects ofpreventing stripping of seals, and preventing excessive pressure againstthe seals which tends to distort the packing and interfere with the freesliding of the barrel over the packing.

The position of the packing 111 is not only governed by the Well depthand by the amount of lubricant seepage, but also by the amount of wearon the walls of passages 18 and 20. The diameters of these walls should,as pre viously stated, be equal in order that there will be no pistonaction as the outer and inner tubular components are telescoped.However, should these walls wear unequally, the resulting effect islargely compensated by shifting of the position of the sliding packing111.

It is pointed out that as the parts are telescoped, sliding packing 111moves along with the upper mandrel component 112 just as if it weresecured thereto, this being because of the effects of pressure in thewell and inside the tool.

The combined cross-sectional areas of the lubricant passages 132 (or2133 after the relative positions of the mandrel and drive sleeve havebeen rotationally shifted) should be above a certain minimum. Thisminimum depends largely upon the cross-sectional area of the lubricantchambers 134 and 136, as viewed in a horizontal plane. For constructions(such as both of the embodiments described in this application) in whichthe cylinder containing the outer mandrel spline surfaces (numbered 129in FIGURE 15) is spaced approximately midway between the wall of passage18 or 20 and the outer surface of the central mandrel portion (numbered127 in FIGURE 15), it has been found that the combined crosssectionalarea of the passages is preferably at least 25% of the combinedcross-sectional areas of the mandrel and drive splines, all as viewed ina horizontal plane. Stated otherwise, the passage area should preferablyadd to at least 20% of the total annulus (defined between surface 127and the wall of passage 24 in FIGURE 16). Although these minimumpercentage areas are preferred, it has been found that in certainapplications the passage area may be as little as 10% of the totalannulus. The first embodiment, as shown in FIGURE 7, is very much aboveminimum. The second embodiment, as shown in FIGURE 16, is alsosubstantially above the minimum, since three twelfths or 25% of thetotal annulus is occupied by the passages 132. Also, the passages 132have a combined cross-sectional area of 33 /3% of the splines, therebeing three gaps or passages and mine mandrel and drive splines.

The above minimum passage area will be increased where thecross-sectional area of chambers 1134 and 136 (as viewed in a horizontalplane) is increased and may be decreased somewhat when such chamberareas are decreased. This assumes that knocker head 103, and theshoulder above packer 119, vary in size with the passages in which theyslide. There should be free communication between the chambers 134 and136 at all times, regardless of the relative longitudinal positions ofthe inner and outer tubular components.

It is to be understood that the present apparatus does not requirepumping of liquid longitudinally of splineways (such as number 52 inFIGURE 5) which are occupied by splines (such as number 25 in FIGURE 7).This is because the internal diameter of the surrounding tube portion,above and below the area x in FIGURES 1 and 3, is in each instancesubstantially larger (FIG- URE 8) than the maximum mandrel diameter atthe splines. The liquid may therefore flow transversely orcircumferentially over the outer curved surfaces of splines 50 and 51,from splineways 52 into spaces z, without creating a damping or dash potaction.

Various embodiments of the present invention, in addition to what hasbeen illustrated and described in detail, may be employed withoutdeparting from the scope of the accompanying claims.

I claim:

1. In an oil tool for use during normal drilling operations, thecombination of inner and outer telescopically connected tubes movablelongitudinally, means for connecting the outer tube to a drillingstring, the inner tube having an end below the outer tube for connectionwith an object in a well bore, spline means upon said tubes to preventrelative rotation of the same and permitting their free relativelongitudinal movement, said tubes being formed to provide a lubricantreceiving chamber therebetween along the spline area, packer meanssealing said chamber at its ends above and below the spline area, saidtubes between said packer means having an unobstructed large-areapassageway along the spline area for free flow of lubricant along saidpassageway as the tubes are axially reciprocated relative to each other,the inner tube having a striking surface facing upwardly and the lowerend of the outer tube having a striking surface facing downwardly forcontact with the first mentioned striking surface upon downward movementof the outer tube relative to the inner tube, a knocker head carried bythe inner tube within the outer tube for longitudinal movement with theinner tube and located in and across said chamber, said knocker headhaving a downward-1y facing striking surface and the outer tube havingan upwardly facing striking surface in position for engagement with thestriking surface of the knocker head upon upward movement of the outertube relative to the inner tube.

2. A bumper sub as described in claim 1 in which the knocker head liesappreciably below the upper packer means to provide a reservoir abovethe knocker head for receiving lubricant, said knocker head havingsliding sur- 1 ace contact with the inner walls of the outer tube toprevent angled wobbling of the tubes, said knocker head having apassageway for flow of lubricant from said reservoir to the spline areachamber.

3. In an oil well drilling tool, the combination of a lower barrelportion having a passageway therethrough, a drive sleeve detachablyconnected to the lower end of said barrel portion and having apassageway therein and a first striker surface facing upwardly in thepassageway of said barrel, a mandrel tube having a drilling fluidpassageway therethrough, said mandrel tube being slidably disposed inthe passageways of the barrel and drive sleeve, said mandrel beingspaced from the inner walls of the barrel and drive sleeve to provide alubricant chamber, upper packing means mounted upon said mandrel andoperating within the passageway of the barrel substantially above saidfirst striker surface and in sliding sealed contact with the wall ofsaid passageway, lower packing means mounted upon the mandrel andslidably operating in sealed contact with the inner wall of the drivesleeve, said mandrel having an upwardly facing striker surface thereonand disposed exteriorly of said chamber, said drive sleeve having asecond striker surface provided thereon exteriorly of said chamber belowsaid first striker surface for impact with the striker surface of themandrel, spline means connecting the mandrel with the drive sleeve atthe upper portion of the drive sleeve to permit free reciprocation ofthe mandrel within the barrel and drive sleeve and to prevent rotationof the mandrel within the barrel and drive sleeve, 21 knocker headcarried upon said mandrel above said first striker surface of said drivesleeve, said knocker head being located below said upper packing means,and means to permit the free non-bufling interchange of lubricant alongthe spline area of said mandrel and drive sleeve incident toreciprocation of the drive sleeve upon the mandrel.

4. A tool as described in claim 3 in which there is provided anauxiliary lubricant reservoir in the barrel above the knocker head, saidknocker head being formed with passage means therethrough to permit thelubricant to flow into the sealed chamber at the spline connecting areaof said chamber for replenishing lubricant therein.

5. A bumper sub comprising an outer tube having a passageway therealong,an inner tube having a fluid passageway therethrough, spline meansconnecting said tubes to permit the axial movement thereof and toprevent relative rotational movement thereof, the outer tube having anupwardly facing striker surface, the inner tube having an annular grooveexternally therein above said striker surface and spline means, and asplit knocker head ring held in said groove against lengthwise movementand having a downwardly facing striker surface for impact with thestriker surface first mentioned, said split knocker head ring having aclose sliding fit upon the inner Walls of the outer tube to preventrelative 11 wobbling of said tubes, the split of said ring forming apassageway for lubricant fiow from above the knocker head to the splinearea below the knocker head.

6. As an article of manufacture a mandrel for bumper subs comprisingmeans at the lower end thereof for connection with a bit or otherobject, said mandrel being of elongated tubular form and at the lowerend thereof above said means having an upwardly facing striking surface,said mandrel above said striking surface having an external annularpacking ring receiving groove therein, the mandrel above said groovehaving elongated spline ways provided therealong and above said splineways having an annular under cut knocker head receiving groove, andmeans externally at the upper end of the mandrel above the lastmentioned groove for supporting a packer ring.

7. In a tool for imparting jarring actions to drilling strings forfreeing stuck bits, drill collars and other objects within a well bore,the combination of an outer tube having a downwardly facing strikersurface at its lower end and having a passageway therein providedintermediate the ends of the tube with an upwardly facing internallyspaced striker face, a mandrel tube slidably disposed within thepassageway of the outer tube, a knocker head carried by the mandrelabove the inner striker surface of the outer tube having a downwardlyfacing striker surface for the upwardly facing striking surface of theouter tube, said mandrel at its lower end projecting below the outertube and having an upwardly facing striker surface for the lowerstriking surface of the outer tube, packer means carried by the mandrelabove the knocker head for sealing action in the passageway of the outertube, interfitting spline means upon the outer surface of the mandreland the inner surface of the outer tube to prevent relative rotation ofthe outer tube and mandrel, packer means upon the mandrel below thespline means engaging the inner walls of the passageway of the outertube, said tool between the packer means defining a sealed chamber forreceiving lubricant, said mandrel being provided with large area openedspline passages therealong at the spline connected area of the mandrelwith the outer tube to permit free flow of lubricant along the splinearea as an incident of relative axial reciprocation of the mandrel andouter tube.

8. A tool as described in claim 7 in which an auxiliary lubricantreservoir is provided in the outer tube between the same and a reducedportion of said mandrel, and between the knocker head and upper packer,said knoeker head having passage means therethrough for flow oflubricant from said reservoir for replenishing the supply of lubricantto the spline area chamber in said tool.

9. A bumper sub for connection in an oil well drilling string near thebottom thereof, said bumper sub being adapted to be used constantlyduring normal drilling operations to maintain a constant weight upon thedrill bit, to absorb the shocks caused by jumping and whipping of saidbit, and to produce object loosening jarring when necessary, whichbumper sub comprises outer and inner tubular parts disposed intelescoped relationship, said parts having radially spaced surfacesdefining between them a lubricant receiving chamber, upper and lowerpacker means provided between said parts at the ends of said chamber andserving to seal said chamber, longitudinal spline or key meansconnecting said outer and inner parts to prevent rotation thereofrelative to each other while permitting free longitudinal movemrnttherebetween, said spline means being continuously engaged while saidbumper sub is in the well, said spline means being disposed in saidchamber for lubrication by lubricating fluid therein, stop means tolimit the amount of upward and downward longitudinal movement of saidouter and inner parts relative to each other, and large area passagemeans for effecting at all relative positions of said outer and innerparts free and unobstructed transmission of lubricating fluid betweenopposite end portions of said spline means, said passage meanspreventing said lubricating fluid from effecting a damping or dash potaction during telescoping movement of said outer and inner parts, saidpassage means being adapted upon assembly of said parts in differentrelative rotated positions to serve as splineways for spline portions ofsaid spline means.

10. The invention as claimed in claim 9, in which said passage meanscomprises gaps between portions of said spline or key means, said gapshaving a combined minimum cross-sectional area at least 25% as great asthe cross-sectional area of said spline or key means.

11. The invention as claimed in claim 9, in which said stop meansincludes a knocker head mounted on said inner part in said chamber andabove said spline or key means, and in which lubricant transmittingpassages are provided to effect feeding of lubricant to said spline orkey means from the portion of said chamber above said knocker head andbelow said upper packer means.

12. In an oil well tool, an outer generally tubular component, an innergenerally tubular component reciprocably mounted within said outercomponent, the outer wall of said inner component being spaced from theinner wall of said outer component to define a lubricant chambertherebetween, means to conduct fluid through said inner component,sealing means provided between said outer and inner components at oneend portion of said lubricant chamber for preventing entrance ofundesired fluid into said lubricant chamber, and a pressure-equalizingsliding packing provided between said outer and inner components at theother end portion of said lubricant chamber for prevention of entranceof undesired fluid into said lubricant chamber, said sliding packingbeing mounted between said inner and outer components for free slidingmovement relative to both of said inner and outer components, saidsliding packing comprising a rigid ring mounted around said innertubular component for free-sliding movement relative thereto, sealingmeans provided in said ring for engagement with said inner component andconsequent prevention of leakage between said ring and said innercomponent, and packing means provided in said ring for engagement withsaid outer component and consequent prevention of leakage between saidring and said outer component.

13. In an oil well tool, an elongated outer member and an elongatedinner member telescopically associated with each other, means to definefirst and second lubricant chambers between said outer and inner membersand longitudinally spaced from each other, and spline or key meansprovided on said members between said first and second chambers, saidspline or key means being continuously meshed for preventing rotation ofsaid members relative to each other while permitting longitudinalmovement of said members relative to each other, said spline or keymeans including a plurality of splines on said inner member and aplurality of splines on said outer member extending longitudinallythereof in meshed relationship, said splines being so spaced and relatedthat the spaces or gaps between adjacent splines of one of said membersserve selectively as splineways and lubricant passages for transmissionof lubricant between said first and second lubricant chambers, inaccordance with the rotated position at which said inner member isassembled relative to said outer member prior to introduction of thetool into the well.

14. The invention as claimed in claim 13, in which the splines on saidouter and inner members are both equally spaced, and in which the numberof splines on one of said members is a multiple of the number of splineson the other of said members.

15. In a bumper sub for use in oil well drilling operations, an outertubular element comprising a barrel and a drive sleeve coupled togetherin longitudinal relationship, a mandrel reciprocably mounted within saidouter tubular element and provided with external longitudinal splineelements equally spaced about the outer surface of said mandrel, saidspline elements being relatively long, and a plurality of relativelyshort longitudinal splines formed internally on a portion of said drivesleeve adjacent the coupling with said barrel, said splined drive sleeveportion being removably coupled to an additional portion of saiddrivesleeve relatively remote from said barrel, said drive sleevesplines being equally spaced about the mandrel and being continuouslymeshed while the bumper sub is in the well in spaced splineways betweenmandrel spline elements, whereby the remaining splineways betweenmandrel spline elements are free of drive sleeve splines and formlubricant passages for transmission of lubricant between spaced portionsof said bumper sub.

16. The invention as claimed in claim 15, in which the mandrel splineelements are six in number and are each 30 in width separated by a 30gap, and in which the drive sleeve splines are three in number and areeach 30 in width separated by a 90 gap.

17. A bumper sub for connection in an oil well drilling string near thebottom thereof, said bumper sub being adapted to be used constantlyduring normal drilling operations to maintain a constant weight upon thedrill bit, to absorb the shocks caused by jumping and whipping of saidbit, and to produce object-loosening jarring when necessary, whichbumper sub comprises outer and inner tubular parts disposed intelescoped relationship, said parts having radially spaced surfacesdefining between them a lubricant receiving chamber, upper and lowerpacker means provided between said parts at the ends of said chamber andserving to seal said chamber, at least one of said packer means beingadapted to slide freely relative to both of said outer and inner partsin order to provide a pressure-equalizing action between said chamberand the drilling fluid, longitudinal spline or key means connecting saidouter and inner parts to prevent rotation thereof relative to each otherwhile permitting free longitudinal movement therebetween, said splinemeans being disposed in said chamber for lubrication by lubricatingfluid therein, stop means to limit the amount of upward and downwardlongitudinal movement of said outer and inner parts relative to eachother, and passage means for eifecting at all relative positions of saidouter and inner parts free and unobstructed transmission of lubricatingfluid between opposite end portions of said spline means, said passagemeans having a combined minimum cross-sectional area at least as greatas the combined cross-sectional area of said spline means and passagemeans, said passage means preventing said lubricating fluid fromelfecting a damping or dash pot action during telescoping movement ofsaid outer and inner parts.

18. The invention as claimed in claim 17, in which said stop meansincludes a knocker head comprising split ring elements mounted on saidinner part in said chamber and above said spline or key means, and inwhich said split elements are spaced apart at their ends to providelubricant-transmitting passages effecting feeding of lubricant to saidspline or key means from the portion of said chamber above said knockerhead and below said upper packer means.

19. In a bumper sub for connection in an oil well drilling string nearthe bottom thereof, said bumper sub being adapted to be used constantlyduring normal drilling operations to maintain a constant weight upon thedrill bit, to absorb the shocks caused by jumping and whipping of saidbit, and to produce object-loosening jarring when necessary, whichbumper sub comprises outer and inner tubular parts disposed intelescoped relationship, said parts having radially spaced surfacesdefining between them a lubricant-receiving chamber, apressure-equalizing sliding packing provided between said outer andinner parts at one end of said lubricant chamber and adapted to slidefreely relative to both said outer and inner parts, means to seal theother end of said lubricant chamber, spline or key means provided insaid lubricant chamber and longitudinally of said parts, said spline orkey means permitting longitudinal or telescoping movement of said outerand inner parts relative to each other but preventing rotation of saidouter and inner parts relative to each other, and large area passagemeans provided between the portion of said lubricant chamber on one sideof said spline or key means and the portion of said lubricant chamber onthe other side thereof, said passage means serving to prevent at allrelative positions of said outer and inner parts operation of lubricantto eflect a damping or dash-pot action, and to prevent said lubricantfrom interfering with the position or pressureequalizing operation ofsaid sliding packing,

20. The invention as claimed in claim 19, in which a knocker head isprovided in said chamber and fixedly associated with said inner part forstriking engagement with a strike surface on said outer part, and inwhich passage means are provided to effect transmission of fluid throughsaid knocker head, said knocker head being disposed between said slidingpacking and said spline or key means.

21. In a bumper sub for connection in an oil well drilling string nearthe bottom thereof, said bumper sub being adapted to be used constantlyduring normal drilling operations to maintain a constant weight upon thedrill bit, to absorb the shocks caused by jumping and whipping of saidbit, and to produce object-loosening jarring when necessary, whichbumper sub comprises a barrel and a drive sleeve coupled together inlongitudinal relationship, a mandrel mounted longitudinally within saidbarrel and drive sleeve and provided with a central passage fortransmission therethrough of drilling fluid received from the upper endof said barrel, a pressureequalizing sliding packing provided betweensaid mandrel and barrel at the upper end of said mandrel, said packingbeing freely slidable relative to both said mandrel and barrel, packermeans provided at the lower end of said mandrel for sliding sealingengagement with the interior wall of said drive sleeve at the lowerportion of said drive sleeve, said sliding packing and said packer meansserving to seal a lubricant chamber defined between said mandrel andsaid barrel and drive sleeve, relatively long longitudinal splinesprovided externally on said mandrel in said lubricant chamber,relatively short internal splines provided at the upper portion of saiddrive sleeve and meshing with said mandrel splines to prevent relativerotation between said mandrel and drive sleeve while permittingtelescoping movements therebetween, large area passage means providedbetween the splines of at least one of said telescoped elements andserving to effect transmission of lubricant between opposite endportions of said lubricant chamber, said passages being suflicientlylarge to permit free lubricant movement therethrough at all relativelongitudinal positions of said mandrel relative to said barrel and drivesleeve for prevention of dash-pot action therebetween, a knocker headfixedly mounted on said mandrel beneath said sliding packing and adaptedto engage a strike surface at the upper end of said drive sleeve uponshifting of said mandrel to a relatively open position relative to saidbarrel and drive sleeve, strike surface means provided between the lowerportions of said drive sleeve and said mandrel for engagement uponshifting of Said mandrel to a relatively closed position relative tosaid drive sleeve, and passage means provided through said knocker head.

22. The invention as claimed in claim 21, in which the cross-sectionalarea of the portion of said lubricant chamber below said knocker headand above said drive sleeve splines is constant and is equal to thecross-sectional area of the portion of said lubricant chamber below saiddrive sleeve splines, the latter area also being constant, suchcross-sectional areas being relatively small in comparison to thecross-sectional area of the portion of said lubricant chamber betweensaid sliding packing and said knocker head.

23. The invention as claimed in claim 21, in which said drive sleevesplines are equally spaced, and said mandrel splines are also equallyspaced and are twice as numerous as said drive sleeve splines, the gapsbetween said mandrel splines being equal in size to said drive sleevesplines and serving selectively as splineways for said drive sleevesplines and as lubricant passages.

24. The invention as claimed in claim 21, in which the lower portion ofsaid drive sleeve is removably secured to the upper splined portionthereof, and in Which the inner diameter of said lower portion is equalto the inner diameter of said barrel.

References Cited in the file of this patent UNITED STATES PATENTS1,798,480 McCullough Mar. 31, 1931 1,801,673 Knox Apr. 21, 19311,900,932 Hollestelle Mar. 14, 1933 2,096,135 Raymond Oct. 19, 19372,585,995 Brown Feb. 19, 1952 2,645,459 Sutliff July 14, 1953 2,721,056Storm Oct. 18, 1955 2,818,232 Osmun Dec. 31, 1957 2,828,944 Udry Apr. 1,1958 2,891,77 Segelhorst June 23, 1959

